Basic Electronics Questions. AMC7135

[Sigurthr]

The cap adds hysteresis, which prevents the chip's internal error amplifier from over-correcting to small changes in the load and supply. Much like ripples in a pool of water if you add in more energy than the system wicks away then the waves increase in height, so too the amplifier overreacting causes run-away oscillation.

In non or low frequency pulsed DC systems the inductance of the wiring is negligible (other than to cancel out self-capacitance of the wires), if it were a HF AC or fast rise time pulse system the inductance would cause spikes that capacitance can absorb.

 

[Bionic-Badger]

Schweet. I will hold off on ordering some PCBs until i test my design on a protoboard or something

When you design your board, design it using a schematic in Eagle first. That way you'll be sure your wiring is correct and as you expect. Of course that'll require learning to read and write schematics, but that should be important to learn anyway.

Nothing worse than sending a design off to get fabricated, waiting a couple weeks for it to arrive, and then finding out it doesn't work at all and not even knowing what went wrong or what could have. Then you're stuck with a bunch of useless fiberglass boards that aren't even big enough to be used as coasters.

Plus, on the breadboard you can work out problems such as whether you need extra parts like capacitors to keep down the noise, or whether you really want 2x driver chips instead of just one, or even if the chip you wanted thought you wanted to use really lived up to your expectations. Plus, you'll have a working circuit to troubleshoot the boards against if something does go wrong.

 

[jimdt7]

Just got my chips from Fasttech but there seems to be a problem...
Here is my setup:
Vin: 4V
TestLoad-Drop: 3V
1x AMC-7135 Chip
But the output is 220mA...
Same thing happening with a cheap 2x 7135 driver from FastTech. (Vin=4V but Iout=360mA instead of 700mA)
Is this normal? :thinking:

Jim

 

[Zeebit]

I had one of those 2xAMC7135 drivers from FT and it had the same problem. I powered it with a single 18650 and hooked it up to a generic 3W led and it was only driving it at around 300mA. I shorted it to my multimeter in Amps mode and its the same thing.

These could be knock-of chips.

 

[jimdt7]

I'm back with even better results! :crackup:
AMC-7315 (350mA)---> Vin=4.5V Iout=335mA with 3V Test-Load Drop
"Binned" AMC-7135 (380mA)---> Vin=4.5V Iout= 330mA with 3V Test-Load Drop
Except from these "binned" chips being the same with the regular ones both of them seem to have a Vref of 1.7V....worse than the LM317...total FAIL! :beer:

Jim

 

[djQUAN]

I dunno. The ones I got from FT work just fine.

 

[jimdt7]

Verified my results using a Sanyo 2400mAh 18650 battery just in case...same thing again! :thinking:
Either there is something wrong with my wiring (too long wires???) or I got a bad batch? :/

Jim

 

[Sigurthr]

I doubt it is your wiring or wire length. Most probably they are knock off chips, which is common.

 

[40mikemike]

This is my interpretation of the the earlier provided link. Sorry i only have Paint.exe right now as i just reinstalled my OS cause my SSD failed.

Is this correct?

Is the out pin the +LD input or is the Vdd the +LD input?

Thanks
-Matt

So could i use an 47 uf 10v??? Please answere quick because I’m in the middle of this project.

 

[40mikemike]

So could i use an 47 uf 10v??? Please answere quick because I’m in the middle of this project.

How about a 1st 16v? This one is very small and can fit In my keychain laser So if it works, this is what will most likely go in.

 

[thanhtung]

This is my interpretation of the the earlier provided link. Sorry i only have Paint.exe right now as i just reinstalled my OS cause my SSD failed.

Is this correct?

Is the out pin the +LD input or is the Vdd the +LD input?

Thanks
-Matt

Like same this is ok!

https://flic.kr/p/2nPJGE3

 

[thanhtung]

Just got my chips from Fasttech but there seems to be a problem...
Here is my setup:
Vin: 4V
TestLoad-Drop: 3V
1x AMC-7135 Chip
But the output is 220mA...
Same thing happening with a cheap 2x 7135 driver from FastTech. (Vin=4V but Iout=360mA instead of 700mA)
Is this normal?

Jim

me too ! but idk why's like that! but when you connect 3 x acm7135 --> you have still gotten ~800-1000mW red 638nm